Cosmetic stick damage is a continuing problem for the manufacturers of cosmetic dispensers. Cosmetic stick damage is often the result of excessive play among the components of the dispenser, which can cause the cosmetic stick to wobble and impact the inner walls of the dispenser, causing damage to the stick. For example, a lipstick pomade is a relatively fragile product which may be broken by such impact. Another problem is "pomade back-off" which arises when a consumer applies lipstick and holds only the lower portion of the case. A downward force is applied to the elevator cup by the pressure of the consumer's lips against the pomade. This causes the elevator cup and pomade to to be forced down into the dispenser case.
Conventional propel/repel lipstick dispensers typically have an outer helical cam track sleeve and a longitudinal track innerbody rotatable inside the cam sleeve to axially propel and retract an elevator cup with a lug or lugs that track in the cam track and in the longitudinal track. One such conventional dispenser is disclosed, for example, in Hultgren, U.S. Pat. No. 3,298,509.
In these conventional dispensers there is often a clearance between the lower end of the elevator cup and the innerbody due to the molding requirements and the shrinkage of the plastic parts after molding. This clearance is sufficient that the cup may wobble inside the innerbody, and this wobble can lead to damage to the cosmetic pomade during shipment.
It is known in the art to provide cosmetic dispensers such as lipstick cases that have a particular frictional "feel" to the consumer operator when the dispenser is operated to extend or retract the cosmetic stick. It is desirable that the swivel torque needed to rotate the dispenser components to dispense the lipstick be as nearly constant as possible, regardless of whether the dispenser is nearly full or exhausted of the cosmetic. The swivel torque should be significant enough to impart a firm feel to the dispenser. Looseness, uneven drag, or inconsistency of torque can be interpreted by the consumer as indicating an inferior quality product.
The prior art has attempted to provide the desired firmness and consistency of swivel torque by a number of devices. U.S. Pat. No. 4,750,501 to Ackermann et al. is an example of one type of cosmetic applicator wherein an objective is to impart an even drag and swivel torque during operation.
In other prior art devices, two lugs or tabs are provided on the elevator cup to press against the innerbody or the cam sleeve to provide frictional interference therebetween, and also ribs have been provided on the innerbody that frictionally fit against the elevator cup. However, these prior art devices have generally suffered from inconsistent swivel torque along the travel of the elevator cup as it moves from the extended to the retracted position. This problem arises because the effective inner diameter of the innerbody can vary along its length and thereby vary the swivel torque in an undesirable manner. The dispenser can therefore tend to feel looser when the cup is at one end and tighter when the cup is at the other end.